Torsion balance



April 19, 1938. E. REEH 2,114,769

TORSION. BALANCE Fiied Oct. 9, 1936 Jnvenzon tented Apr. 19, .1938

TQRSION BALANCE lErich Hanoven.

Application October 9, 1936, Serial No. 104,869 In August 13, R35

1 Claim. (Cl- 265-45) sion balances. 1-

The exactness of measurements obtained by means of the usual torsionbalances is injured by different phenomena, chiefly by variations oftemperature which occur during the measuring operation and whereby aircurrents are produced.

In order to insure the measurements against the influence of variationsof temperature caused by air currents the proposal has been made-tosurround the pendant with a number of thin walled metallic boxes orpipes which in turn are separated from one another by air spaces and arenot connected by metallic material.

Attempts were made to make the casing of a bad conductor of heat, but itwas found that such materials are not uniformly heated so that the innerwalls show marked differences in tem- .perature.

This invention relates to improvements in tor- 20 According to thepresent invention the pendant is disposed in a metallic casing the wallsof which have a thickness substantially equal to or greater than thediameter of the space in which the oscillation takes place. I

'25 Whereas the most sensible of the usual torsion balances are subjectto an average error of about 0.5 are minute in adjusting the beam, thiserror may be reduced to 0.11 are minute by disposing the pendantaccording to the present invention 30 in a metallic casing the' walls ofwhich have a thickness of about 1.7 times the diameter of the spaceofoscillation.

The invention is based on the discovery that the flow of heat in theinterior of a thick wall is more uniform than that in a thin w'all.

Moreover it was found that the damping can be varied by insertingthin-walled tubes fitting into one another so as to touch ione anotherwith 40 their inner and outer surfaces, the flow of heat from metal tometal not being impeded. More or fewer of these tubes may be removed tovary the width of the space where the oscillation takes place, therebyalso varying the degree of damping.

4 damping.

of said beam? The invention is illustrated by way of example in theannexed drawing of which I Fig. 1 shows a longitudinal cross-section ofa casing including the pendant, and Fig. 2 is a cross-section on theline A-B of Fig. 1. I 5 a is the torsion wire, b a mirror connected withthe pendant, c the carrier of the cross-beam. d designates the beam ofthe balance, at the ends of which are secured the heavy bodies 1 e, e. fis the casing surrounding the space of 10 oscillation g, h is a tubefitting into the casing.

Owing to the reduction of the error of adjustment according to thepresent invention it is also possible to shorten the time of calmingdown by diminishing the moment'of inertia and in creasing thecoeflicient of torsion. In this case the sensibility of 1.10 dyn per0.01- cm. of defiection may beretained whilst considerably reducing thetime of 'calming down.

For making the casing, preferably a metal of good heat conductivity ischosen, as, for instanme, copper, phosphor bronze, aluminum or silver.'Aluminum is particularly adapted for the purpose of the inventionbecause when using it the weight of the torsion balance is notconsiderably increased as compared with the weight of the usual torsionbalances.

'The specific heat of the metal employed likewise influences thebalances made in accordance with the invention inasmuch as by absorbingor withdrawing a certain quantity of heat the temperature is onlymoderately aflected in case the specific heat of the material of thecasing is In this respect again aluminum is very wellu 5 qualified owingto its high specific heat.

I claim:

A torsion balance comprising a pendant in cluding a cross beam and asupporting filament therefor, a homogeneous casing of high heatconductivity enveloping said balance, the thickness of said casing atleast approximating the diameter of the space provided therein foroscillation ERICHREEH.

